The development and evaluation of a high brightness field ionization source for high resolution proton microscopy will be pursued. Initial resolution objectives will be modest so that substantial effort can be given to the evaluation of image mechanism and specimen degradation of biological samples. With existing electrostatic lenses we expect to attain a resolution of approximately less than 100 A and sufficient current to examine biological specimens by reflected secondary electron and transmitted proton microscopy. Based on the success of these initial objectives, the field ion microprobe will be analyzed for use with higher resolution ion optics to take advantage of its intrinsic high resolution capabilities.